1. Field of Invention
This invention is directed to cooling containers for beverages and other foods. More specifically, it is directed to double-walled containers that hold a quantity of a chillable or freezable fluid, typically water, between the walls, which can be cooled or frozen without damage to the container. Once frozen, the container cools and keeps cold beverages or foods.
2. Description of Prior Art
Fruit juices, soft drinks and other beverages that are drunk cold are generally served with ice cubes in them to make or keep them cold. A disadvantage of this practice is that only a limited amount of ice can be used in the beverage container, there being a trade-off between the amount of ice used and the amount of the beverage desired. Another disadvantage is that, as heat is transferred from the beverage to the ice, the ice melts, diluting the beverage.
A present practice that avoids these disadvantages is the chilling or frosting of mugs or other containers, so that the beverage may be kept cold by means of contact with the container itself. The disadvantage to this "chilled mug" method is that the container warms up relatively quickly, and therefore its usefulness in keeping the beverage cold is short-lived.
Thermos or other double-walled containers with dead air or vacuum cavities keep beverages cold for relatively long periods. Because such containers depend upon the insulating effect of the air or vacuum, however, they cannot be kept open for appreciable lengths of time, because the insulating effect is frustrated by contact of the beverage with room-temperature air. Moreover, such Thermos-type containers are passive only; that is, they can maintain the temperature of a beverage, but are not useful for chilling a warm beverage.
Some devices utilize a liquid refrigerant in a cavity within the containers, but include air space within the cavity to accommodate expansion of the refrigerant upon freezing. A distinct disadvantage of this type of arrangement is that such devices must be frozen upside-down, since the sides freeze before the bottom; if frozen upright, the air space is at the top of the refrigerant cavity, and the lower end of the vessel will rupture upon freezing of the mass of refrigerant at the bottom. Moreover, in these devices the air space in the refrigerant cavity constitutes some 15-20% of the total volume of the cavity, thereby limiting the amount of volume available for refrigerant, and in fact displacing the refrigerant with an insulating material, decreasing the cooling effectiveness of the container.
A cooling container utilizing a fluorinated hydrocarbon as a refrigerant, as in the device of J. R. Coleman disclosed in U.S. Pat. No. 3,394,562, is undesirable for beverages, because of the danger that the toxic refrigerant will leak into the beverage. The Coleman device cannot be utilized with an aqueous refrigerant because no stress-relieving mechanism is provided to accommodate expansion upon freezing.
The cooling arrangement disclosed by Held, et al. in U.S. Pat. No. 4,357,809 uses a compressible styrene to accommodate expansion of a solid gel refrigerant. The Held device cannot be used with an aqueous refrigerant because the refrigerant diffuses into the styrene, causing the styrene to lose its compressibility, and rupture of the container may result. Furthermore, insulating vacuum pockets would form in the refrigerant cavity, lessening the cooling effectiveness.
It is therefore an object of this invention to provide a double-walled cooling container for beverages and other foods with a fluid refrigerant in the cavity formed by the double-walled structure, such that when the container is chilled or frozen, a stress-relieving mechanism will accommodate the consequent expansion of the refrigerant with neither permanent deformation of the mechanism nor damage to the container.
Another object of this invention is to provide a cooling container for beverages that vitiates the necessity of using ice to cool the beverages, allowing for a rapid and longer lasting cooling effect without dilution of the beverage.
Another object of this invention is to provide a cooling container that can be frozen in any position without damage to the container.
Another object of this invention is to provide a cooling container with a refrigerant cavity that contains no air or vacuum, allowing for greater cooling effectiveness.
Another object of this invention is to provide a cooling container that uses a non-toxic liquid as its refrigerant.
Other objects, advantages, features and results will more fully appear in the course of the following description.